426 HEMI engine

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426 HEMI
Manufacturer Chrysler
aka Type aka here, not up there
Type Gasoline
Production/Introduction 1962
Status "Discontinued"
Displacement 426 cu-in.
Aspiration Natural
Configuration V
Cylinders 8
Fuel System 2-4V Carburetor
Lubrification indicate the engine's type of lubrification
Output 425 hp @ 5000 rpm
N/A lb-ft. of torque @ N/A rpm

490 hp @ 4000 rpm
N/A lb-ft. of torque @ N/A rpm
Bore 4.2500 in
Stroke 3.750 in
Compression 10.25:1
In. Valves 2.25
Ex. Valves 1.94 in
Firing Order 1-8-4-3-6-5-7-2
Left Bank 1-3-5-7
Right Bank 2-4-6-8
Length in inches
Diameter in inches
Width in inches
Height in inches
Dry Weight 843 lb
Fuel Consumption city/highway (mpg & km/L)
Emission/s CO: g/km
CO2: g/km
NOx: g/km
Hydrocarbon: g/km
Particulate: g/km
Chief Engineer write here

The roots of the 426 Hemi go back to 1962, when Chrysler execs identified the need, for an improved competition engine, intended to dominate stock car racing, particularly the highly competitive NASCAR series. At the time, Chrysler was locked in battle, with Ford, Chevy and Pontiac, for racing wins, which were felt to influence new car sales. While the then-current wedge designs were competitive, Pontiac’s Super Duty, and Ford’s 427 were turning up the heat, and the looming introduction of Chevrolet’s 427 CID Mk. IV ‘mystery motor’ (the precursor of the modern Big Block Chevy), promised stiffer competition in the coming years.

Thus, Chrysler engineers went to work, in January 1963, on an engine intended to provide the horsepower to win, despite the increased competition from brand X. The designers were given the daunting task, of creating an engine that would beat all comers, and, worse, they weren’t given much time to accomplish the feat. The target for introduction of the new powerplant, was February 23, 1964, just over one year away, at the year’s biggest stock car race, the Daytona 500.

However, the engineers had an ace up their sleeves. In the fifties, Chrysler had produced an engine, featuring the most efficient cylinder head design, known for an automotive engine. While the first generation Hemi had been shelved, due to expensive production methods, the design represented not only the traits required, for such a competition engine, but also a scheme familiar to the engineers. The early Hemi, had a long and successful track record, and the engineers had experience with it, in racing situations, including an entry in the Indianapolis 500.

With this in mind, and given the short schedule, the engineers decided to adapt the Hemi cylinder head, to the then-current 426 wedge block. Although the project encountered setbacks (namely problems with cylinder wall cracking, requiring changes in block production) the results were an astounding success. Hemi-powered Mopars finished first, second and third, in the 1964 Daytona 500, establishing a new speed record in the process. The legend of the 426 Hemi was born.

The Hemi cars went on to dominate NASCAR in 1964, but, due to the engine’s limited production, were banned for the 1965 season. Several top Chrysler racers, including Richard Petty, competed in NHRA drag racing, using the drag race version of the Hemi. Meanwhile, Fords reigned supreme in a one-car show on the NASCAR circuit.

For the ’66 season, things would change again. NASCAR rules now dictated that a certain number of engines be produced, to become legal. To meet the requirements, Chrysler initiated the Street Hemi program. Basically, this meant that a detuned version, of the racing power plant, became a production option in certain Dodges and Plymouths. The 426 Hemi returned to the NASCAR ovals, and resumed its winning ways.

On the drag strip, the 426 Hemi met with less initial success, however it would come to have far more impact, in this arena, than in any other. In 1964 and 1965 the first design Hemi, still ruled the fastest class of drag racing, the nitro methane-burning top fuel dragsters. The 426 Hemi, despite its advanced technology, was nearly a half second behind the pace set by its ancestor. The answer came in the form of an accidental discovery.

Don Garlits, perhaps the most famous drag racer, of all time, decided he had ‘had enough’ of the new Hemi, and, attempting to accelerate its demise, advanced the ignition timing far beyond what was considered safe, for the older generation Hemi. To his surprise, the new engine did not fail, but ran dramatically quicker times. After this discovery, the floodgates opened, and within a year, fuel dragsters were running in the low six-second range, nearly one and a half seconds quicker, than the older design. Drag racing sanctioning bodies, most notably the NHRA, have adopted a 500 cubic inch, aluminum block, race engine based on the 426 Hemi design. This “426 Hemi” design engine still dominates top fuel racing (dragsters and funny car), regularly traversing 1,000 feet (less than a quarter mile in order to stop engine explosions) in 3.70 seconds and at speeds of over 325 MPH.

In the years between 1966 and 1971, the availability of the 426 Hemi in many Mopar muscle cars resulted in some of the most outrageous machines ever offered by Detroit.

Perhaps the wildest of these, was a special production run of the compact ‘A’ bodies, the Dart and Barracuda, produced in 1968. As the 426 would not fit in the small cars without special fabrication, the actual installation was farmed out to Hurst industries. Along with the installation of the drag racing version, of the Hemi, many weight saving tactics were employed, including fiberglass hoods, and fenders, lightweight van bucket seats, and even thin window glass. The result was the quickest (1/4 mile ET) production car, produced in America. Initial track times in the eleven-second bracket were the norm, with minimal preparation. These cars still dominate the top class of NHRA Super Stock…with current technologies, and rules, they run times in the eight second range at speeds above 150 miles per hour.

While these cars may have been the supreme examples, any Mopar fitted with the 426 hemi, had the potential to be a winner, both on the track and the street. Unfortunately, every party has to end, and ever-increasing insurance restrictions, and emissions regulations spelled the end of the 426 Hemi era. The last cars factory equipped with the 426 Hemi rolled of Chrysler assembly lines in mid 1971.

However, parts continued to be made for racing, both by Chrysler, and ever increasingly, by aftermarket racing suppliers. While Chrysler did stop producing blocks and heads, for a time, they resumed in the 1990s, and today, racers, or anyone else, can buy a complete 426 Hemi from their local Dodge dealer.



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Chrysler LLC

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HEMIs: 345 cid (5.7 liter) · 370 cid (6.1 liter) · 392 cid (6.4 liter)


HEMIs: 241 cid · 259 cid · 270 cid · 276 cid · 291 cid · 315 cid · 315 cid · 330 cid · 331 cid · 341 cid · 354 cid · 392 cid · 426 cid · 472 cid · 528 cid



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